In recent years, progress in power saving for electric devices has been achieved. With this progress, electric blowers used in the electric devices are required to have higher output power and higher efficiency. In particular, an electric vacuum cleaner, i.e. an electric device, is required to exhibit higher suction power.
Hereinafter, referring to FIG. 14, descriptions will be made regarding a conventional electric blower. The electric blower includes a motor and a fan unit integrally in one unit. The fan unit is airtightly attached to the motor, i.e. hermeticity being held between them. The fan unit is composed of air guide 101, fan case 102, fan 103, and fan case spacer 104. Fan 103 includes suction-side shroud 103a. Fan 103 includes suction port 122 in a center portion of suction-side shroud 103a. 
FIG. 15 is an enlarged cross-sectional view of Z portion shown in FIG. 14. Suction port-side end surface 103b of suction-side shroud 103a that fan 103 includes, is in contact with the outer-peripheral side surface of bellows 104a that fan case spacer 104 includes. Alternatively, suction port-side end surface 103b of suction-side shroud 103a has a very slight clearance of about 0.1 mm or less with the outer-peripheral side surface of bellows 104a. This configuration secures the airtightness, i.e. the hermeticity, between suction-side shroud 103a and fan case spacer 104.
Moreover, fan case spacer 104 is fixed to fan case 102 so as to secure the airtightness with fan case 102. Fan case spacer 104 is fixed to fan case 102, by welding or bonding. In Patent Literature 1, a technology associated with the conventional electric blower is described.
By the way, the conventional electric blower has had the following problems to be solved.
The first one is dimensional accuracy of bellows 104a included in fan case spacer 104. In particular, bellows 104a facing suction-side shroud 103a has a profile which is difficult to ensure a stable dimensional accuracy of its outer-peripheral side surface.
The second one is poor concentricity between fan case spacer 104 including bellows 104a and fan 103 including suction-side shroud 103a, i.e. a low degree of their positioning accuracy with respective to their common axis. This is because fan case spacer 104 is welded to fan case 102 or, alternatively, is bonded and fixed to fan case 102. As a result, the concentricity becomes poorer between the outer-peripheral side surface of bellows 104a and suction port-side end surface 103b of suction-side shroud 103a. 
The third one lies in circularity of bellows 104a. That is, when the electric blower is operated, the motor section thereof generates heat. When fan case 102 is made of metal, the generated heat is conducted to fan case spacer 104 via fan case 102, i.e., the metal material. The thus-conducted heat raises the temperature of fan case spacer 104. Temperature-raised fan case spacer 104 sometimes deforms due to its thermal expansion. Such deformation of fan case spacer 104 can deteriorate the circularity of bellows 104a that forms a part of fan case spacer 104.
The thus-deteriorated dimensional accuracy, such as the poor concentricity and the poor circularity, results in insufficient airtightness between suction port-side end surface 103b of suction-side shroud 103a included in fan 103 and the outer-peripheral side surface of bellows 104a included fan case spacer 104. The insufficient airtightness sometimes causes a reverse flow of air discharged from the outer periphery of fan 103, through a gap between fan case 102 and an upper portion of suction-side shroud 103a included in fan 103. Such a reverse-flow phenomenon leads to an air-leakage into a suction-port portion of fan 103, i.e. suction port 122. As a result, this interferes with the drop in vacuum pressure at the suction-port portion of fan 103, resulting in a decrease in the output of the electric blower. The decrease in the output leads to a reduction in the suction power in an electric cleaner.
Moreover, after fan case spacer 104 has been welded to fan case 102 or, alternatively, fan case spacer 104 has been bonded to fan case 102, fan case 102 is press-fitted into a bracket of the electric blower. In this way, fan case 102 is fixed to the bracket of the electric blower. Fan case 102 is press-fitted into the bracket, in a state that suction port-side end surface 103b of suction-side shroud 103a is in contact with the outer peripheral side surface of bellows 104a included in fan case spacer 104. This means that, when fan case 102 is press-fitted into the bracket, fan case spacer 104 is subjected to stress from the outer peripheral portion of suction port 122. Between fan case spacer 104 and fan case 102, the welding strength or bonding strength enough to accommodate the stress is necessary. In order to secure the necessary welding strength or bonding strength, an area commensurate with the welding strength or bonding strength is needed at which fan case spacer 104 and fan case 102 are welded or bonded to each other.
Accordingly, fan case spacer 104 is then very large in size. Fan case spacer 104 is formed as a molded article.
In addition, the process of welding or bonding fan case spacer 104 to fan case 102 is necessary. Consequently, the manufacturing of the conventional electric blower requires a lot of man-hours.